Wire coating compositions



Patented Mayv 3, 1949 2,409,150 wma coa'rme courosrrrons Willis E. Beak,Burton, Ohio, minor to The American Steel and Wire Company of New Jersey, a corporation of New Jersey No Drawing. Application September 4,1947, Serial No. 772,205

3 Claims. 1

This invention relates to wire coating compositions and particularly toenamel compositions capable of replacing galvanized zinc as a wirecoating.

Compositions of the present invention are especially suited for coatingiron or steel wire for preventing corrosion or rusting. Inasmuch as suchwire is frequently used for baling or package bands, the coating shouldwithstand bending and have sufilciently high shear strength andcoeflicient of friction that knots in the wire have tensile strengthapproaching that of the wire, that is, being within about 85 per cent ofthe latter. In addition the coating must possess satisfactory adhesivequalities and impart a satisfactory resistance to corrosion or rusting.

The present application is a continuation-inpart of my earlier copendingapplication Serial No. 521,273, filed February 5, 1944 (now abandoned),and assigned to the same assignee.

An object of the invention is to provide improved enamel coatingcompositions that may be used on wire in place of zinc coatings and havecharacteristics approaching those of zinc as respects adhesion,corrosion resistance, flexibility and shear strength.

Zinc has certain disadvantages as a coating.

material. It is expensive and likely at times to be in short supply.Zinc is an objectionable material when charged into open hearthfurnaces; hence steel wire coated with zinc has little scrap value.

Accordingly, a further object of the invention is to provide improvedwire coating compositions of inexpensive, relatively abundant materialsthat do not interfere with utilization of wire scrap.

Coating compositions of the present invention consist essentially of thefollowing ingredients in the following proportions to make approximately100 gallons:

Soft red iron oxide lbs 120 to 160 Fibrous magnesium silicate lbs 10 to40 Litharge lbs 5to 25 Aluminum stearate lbs up to 4 Varnish gal 75 to85 Thinner gal 10 to 15 Iron oxide is employed in the composition tofurnish hardness in coating films and, in conjunction with resins in thevarnish, to furnish strength.

Soft iron oxides operable in compositions of the present invention maybe distinguished from harder, inoperable grades by the ease with which 2the material may be ground. A soft oxide ground in a pebble mill for 48hours in a paint or varnish vehicle has a smooth, creamlike texture. Ahard oxide so ground is harsh and grity. -A recognized test in the paintindustry is to grind the material under the conditions mentioned and toobserve the texture by spreading the ground material on a glass platewith a spatula.

Therefore, I deflne the term soft iron oxide as used herein as meaning asubstance having the chemical formula F6203, plus minor impurities, andsusceptible to grinding in a pebble mill in a paint or varnish vehiclefor 48 hours to furnish a product that has a smooth, creamlike texturewhen spread on a glass plate with a spatula. I do not know 01' anymathematical scale by which this hardness difl'erence may be expressed,although the materials usually may be distinguished by their source.Soft oxides used as pigments are usually precipitated from copperassolutions, while hard oxides are usually ground ore.

Fibrous magnesium silicate provides flexibilty in coating films. Thegrade employed is preferably that of needlelike particle structurehaving a specific gravity of around 2.85 and ground to a fineness of 325mesh. Such material is available commercially under the trade nameAsbestine.

, Litharge provides corrosion resistance and also assists in providingflexibility. Standard commercial grades may be employed.

Aluminum stearate is included in the composition to prevent hardsettlingof the solid ingredients when the composition is shipped or stored inprepared liquid form. The material may be omitted from compositions thatare used promptly after preparation, since it is of no benefit in thecoated product.

The varnish is of an oil length of 8 to 18 gallons, the oil length of avarnish being the gallons oi. drying oil per pounds of resin. Apreferred varnish consists of "fine melt" Congo resin and linseed oil inthe ratio of 100 pounds of resin to 15 gallons of oil (oil length of 15gallons). The term -fine m'elt" indicates that the resin has been meltedand heated to temperatures of 600 F. to 760 F. to promote chemicalcombination of the fatty acids and alcohols 01 the resin and boiling onof the excess resins to a 30% loss of weight. Examples of other operableresins are: rosin hardened'with lime; rosin hardened with magnesia andlead or zinc oxide or both; Congo resin esterified with glycerin; estergum; fossil resins, such as Batu; rosin reacted with maleic acid and analcohol; and rosin reacted with phenol-formaldehyde. The last two listedare known in the trade respectively as maleic modified resins" and"phenol-formaldehyde modified resins and are available commercially frommost resin manufacturers. Examples of other operable drying oils aretung oil or perilla oil. The oil'length of the varnish is adjusted inaccordance with the selection of resin and oil to furnish a coatinghaving the desired hardness. In general, the higher the oil length, thesofter the varnish and the less needed in the enamel.

Examples of suitable thinners are naphtha, such as Varnish Maker's andPainter's (V. M. 8: P.), toluol, xylol and certain mineral spirits, andnumerous others that could be named. Thinners are employed in accordancewith standard practice to provide a proper working viscosity and theexact selection or quantity is a matter of convenience to the user.

An example of a preferred enamel composition within the limits disclosedis as follows:

Soft red iron oxide lbs. 140 Fibrous magnesium silicate lbs. 38 Lithargelbs. 19% Aluminum stearate lbs. l to 4 Congo-linseed oil varnish of 15gallon oil length gallons 80 V. M. 81 P. naphtha do 12 Enamelcompositions of this formula and others within the ranges disclosedprovide wire coatings of excellent adherance, flexibility and shearstrength, and impart satisfactory corrosion resistance.

While I have disclosed but certain exemplary enamel compositions, it isapparent modifications may arise. Therefore, I do not wish to be limitedby the disclosure set forth, but only by the scope of the appendedclaims.

I claim:

1. A coating composition adapted to produce a rust resisting coating onan iron wire, which consists of the following constituents insubstantially the proportions indicated:

Soft red iron oxide -lbs. 140 Fibrous magnesium silicate lbs. 38Litharge lbs. 19 /4 Aluminum stearate lbs. l to 4 Congo-linseed oilvarnish of 15 1 gallon oil length gallons Varnish Makers and PaintersNaphtha do 12 /2 2. A coating composition consisting of the followingingredients in the following proportions:

Soft red iron oxide lbs. 120 to 160 Fibrous magnesium silicate lbs. 10to 40 Litharge lbs. 5 to 25 Aluminum stearate lbs. 0 to 4 Varnish gal.'75 to Thinner gal. 10 to 15 said varnish consisting of a resin of thegroup which consists of Congo resin, hardened rosin and ester gum and adrying oil and being of an oil length of 8 to 18 gallons.

3. A coating composition consisting of the following ingredients in thefollowing proportions:

Soft red iron oxide lbs. to Fibrous magnesium silicate lbs. 10 to 40Litharge lbs. 5 to 25 Aluminum stearate lbs. 0 to 4 Congo-linseed oilvarnish of 8 to 18 gallon oil length gal. 75 to 85 Varnish Makers andPainters Naphtha gal. 10 to 15 WILLIS E. BOAK.

No references cited

